Needle for sound reproducing instruments



Sept. 27; 1932.

A. L. WALTQN NEEDLE FOR SOUND REPRODUCING INSTRUMENTS Filed NOV. 10,1930 INVENTOR Gui mm Patented Sept. 2 7, 1932 UNITED STATES ALFREDLEONARD .WALTON, onBLAcKrooL} ENGLAND NEEDLE FOR SOUNDREPRODUCIIQ'GINSTBUMENTS Application filed November 10, 1930. Serial No.494,532.

The invention relates to needles for use in sound reproducinginstruments, and is of the type constructed with a fine wire coresurrounded by a support of relatively softer material, the wire beingadapted to engage the reproducing track of a gramophone record, thesofter casing being adapted to lie on and to be ground away byfrictional contact with the surface of the record.

In this type of needle the perfect trans mission of recorded soundvibrations to the stylus bar and diaphragm of a sound reproducinginstrument is dependent upon the supporting material being of sufiicientstrength and thickness to adequately support the sound box of the soundreproducing instrument; being sufficiently firm to give adequate andcontinuous support to the fine wire core; transmitting the recordedsound vibrations from the record to the stylus bar and diaphragm withoutloosening its grip on the wire core and causing a partial loss of suchvibrations with consequent imperfect reproduction; and being in suchrelation to the wire core as regards surface area that the removal ofsuch supporting material by frictional contact with the surface of therecord will not interfere with the vibrationsat the needle point. I amaware that it has been proposed with the vibrations at the needle point,such supporting material is not of suflicient strength and thickness toadequately support the sound box of the sound'reproducing' instrument. Iam also aware that it has been proposed to use a soft or wearablesupporting material composed of a combination of graphite, beeswax andresin, but such supporting material also fails to satisfy the essentialconditions in that if made sufficiently firm to give adequate andcontinuous support to the fine wire core and transmit the recorded soundvibrations from the record to the stylus bar and diaphragm withoutloosening its grip on the wire corefthe removalv of such sup-; portingmaterial by frictional contact with the surface of the record interfereswiththe vibrations at the needle point, causing a par tial loss of suchvibrations with consequent imperfect reproduction. i 1

"The essential featureof my inventionlies in the wire core beingsurrounded by a firm material which satisfiesall the requiredcon ditionsessential to the perfect transmission of recorded sound vibrations tothe stylus bar and diaphragmof a sound reproducing instrument," in thatthe said supporting mate; rial gives the fine wire core rigid andcontin-' uous support, and is yet sufficiently soft to be I easilyremoved by frictional contact with the surface of the record ofa soundreproducing inStrument-.- I l j r I o According to the invention theneedle com prises'a fine, hard Wire adapted to engage the reproducingtrackof a gramophone rec ord,.and a supporting material whichis com?posed of clay,china clay, or a composition of graphite and china clay,kilned, calcined or baked hard to "give the desired firmness and wearingproperties. v. i

The said wire and supporting material maybe adapted to be mounted directinto the p needle socket of thesoundboxof a so-undre- 1 producinginflstrument,for may be carried in" a'chuck provided with a shankadapted to be held in the needle socket of the sound a sound reproducinginstrument. H

The invention will be fully described with reference to theaccompanying" drawing, in which, for clearness, the needle is drawn toan enlarged scale.

Fig. 1 is an elevation part in section of one form of the invention.

Fig. 2 is an elevationpartly in section of box of another form.

Fig. 3 is a diagrammatic sectional elevation of the needle and record. 7V

The wire a is of a gauge sufficiently fine to lie within the soundgroove of a gramopho-ne record, and is of hardened steel or alloy embedded in and supported by a support I) composed of clay, china clay, ora composition" of graphite and china clay, kilned, calcined or bakedhard toJgive thedesired firmness and wearing properties, the graphiteserving as a lubricant between the needle and the record A when the saidgraphite is worn away by frictional contact with the record.

The support I) is shown fitted into a cylindrivcal chuck 0 provided witha shank d adapted to be held in the needle socket of the sound box of asound reproducing instrument.

In the form shown in Fig. '2, the needle comprised of the fine wire aand calcined support 6 is gripped in asplit chuck 03 over which ataperingcap e is secured to hold it firmly by releasing the cap 0 theneedletmay be withdrawn from the chuck and its length adjusted asrequired. r r 7 The needle is applicable for useon records having alaterally sinusoidal groove or of the hill and dale type as thesupporting material is ground away by frictional contact with the sidesor bottom of the grooves of the record as necessary due to the wear ofthe wire fa and does not interfere withthevibrations of the needle, aWhat I claim as my invention and to protect by Letters Patent is i l. Aneedle for use insound reproducing instruments comprising a fine hardwire core to engage the reproducingtrack of the gramophone and a. casingof calcined material .to rigidly support the core and be worn away byfrictional contact with the, surface of the record.

2. A needle for use in sound reproducinginstruments comprising a finehard 'wire core to engage the reproducing track of the g'ramophone and acasing of calcined china clay torigidly support the core and be wornaway by frictional contact with the surface of the record. I v g 3. Aneedle for use in sound reproducing 1 instruments comprising a fine hardwire core to engage the reproducing track of the gramophone and acasingiof a combination p of graphite and china clay calcined and. bakedhard together, to rigidly support the 7 core and be worn away byfrictional contact with the surface of the record. 7

In testimony whereof I have hereunto set myhand.

' ALFRED LEONARD WALTON.

desire,

